08 Feb 2010
Energy is one of the two commodities that can be considered indispensable for human existence. Energy furnishes human needs and allows humans to live a sustainable life (Sen, 2008). It is the prime mover of productivity as it powers the world’s industries which provide the people with both their basic needs and jobs. Energy comes from different sources. While fossil fuel has been widely used since Industrial Revolution, the potential of solar energy was not given that much attention. People sequester energy from various sources while solar energy which comes freely and has an enormous amount of power was not used extensively as other sources of energy. However, with the current situation of the environment, the world has turn heads on potential alternative sources of energy which can replace fossil fuels. Fossil fuels such as coal, oil and natural gas have been used extensively for hundreds of years because it a conventional source of energy but then again, considering that fossil fuels are non-renewable, exhaustion of sources of these important fuels may hinder future production. More importantly however, fossil fuels are huge contributors to the environmental degradation caused by carbon emissions. Indeed, the use of fossil fuels results to environmental constraints thus explains why tapping clean yet economical alternative sources of energy is necessary. The sun is one of the infinite sources of energy along with wind, water and geothermal energy hence it can be used as a renewable energy source. At the same time, problem with carbon emission would be solved. Solar energy is virtually limitless form of energy which can be harnessed to power the daily activities of humans and while it has not been used exclusively the growing concerns on environmental degradation resulting from the use of fossil fuels bring solar energy into the forefront of alternative energy options.
The potential of solar energy as fuel was recognized even during prehistoric times wherein it was used for domestic needs. The memorabilia of Greek historian Xenophon contain some accounts of the teachings of the Greek philosopher Socrates (470-399 BC) regarding the correct orientation of their homes to make it cool during summer while keeping it warm during winter which is part of his passive solar design (Null, 2009). During prehistoric times, man also recognized that drying their food under the sun would give it longer shelf life. Moreover, they can also utilize the sun’s energy to produce salt from seawater through evaporation. With the benefits of the sun in their lives, the prehistoric people even regarded the sun as god and worship it. Indeed, even during the earliest times of human dwellings on earth, the energy coming form the sun is already recognized beneficial for humans (Hough, 2006). Throughout history, both man and nature benefits from the solar energy. All forms of energy in the world originate from the sun. The fossil fuels that are widely used today such as oil, coal and natural gas initially undergo a photosynthetic process which produces the organic materials needed to be converted into these fuels (Hough, 2006).
In the 18th century, the Industrial Revolution became the prime mover for the utilization of coal and other fossil fuels. With the growing number of industries during that period, there was huge demand for coal and other fossil fuels. However it was also during that period that the first solar motor was developed. The French Mathematician Auguste Mouchout realized than man has been increasingly dependent on fossil fuels and finds an alterntaive fuel. He tracked the sun and focused the rays into a boiler to produced a small steam engine. His work was modified and was continually developed until twentieth century. Mouchout’s solar motor eventually become the basis of the solar energy used in the commercial sector at present which is the concentrated solar power (CSP) (Null, 2009). The energy crisis which ocucured in 1970s led to upsurge of research on alternative energy sources but was specifically focused on solar energy (Sen, 2008).
Traditionally, solar energy has been used in heating and cooling homes and buildings. Large amount of energy are required to heat and cool buildings. Solar energy is considered a viable option for the energy required in heating and cooling buildings especially in countries which has good solar potential (Hough, 2006). Between 1984 and 1990, nine solar thermal electric power plants were built by the LUZ International Limited in Mojave Desert. The electricity produced by these solar power plants was sold to Southern California Edison Company. Although this effort to utilize the solar energy was halted because the LUZ went bankrupt, this shows that there has been considerable effort to finally move away from dependence on fossil fuels (McKinney et al., 2007).
Advantages and Disadvantages of Solar Energy
The sun is the ultimate source of energy that can be used by mankind over and over. It is renewable, unlimited and clean. Although solar energy is not equally distributed around the world, harnessing even a small portion of the enorumous energy from the sun would be enough to solve major energy crisis which has been occuring for many years. Solar energy has many advantages over other forms of energy. Perhaps its biggest advantage is that it is a clean form of energy hence it can be supplied and use without causing environmental pollution. Fossil fuels are huge contributors to the degradation of our environment however it remains in the mainstream in the provision of energy primarily because fossil fuels are cheap and conventional sources. But then again, fossil fuels are considered as non-renewable energy sources. That is, the remaining fossil fuels may not be sufficient to provide for the energy needs of the people in century or two. With this reality in front of us, it is essential to find the best alternative fuel that can possible take the place of fossil fuels when reserves are exhausted. However, in choosing alternative fuels, it is important to make important considerations such as the economic, environmental and associated hazards that could be associated with an alternative fuel use should be placed with high importance. Given the fact that our environment has been suffering from the by-products of fossil fuels, the environmental concerns should be taken into consideration (Hough, 2006).
One of the major disadvantages of solar energy is that sunlight from which the energy is derived is widely dispersed in nature. That is some areas may be fully lighted while others are not. This is the reason why not all countries may be able to harness the sun’s energy as effectively as others. In order to capture a significant amount of solar energy, the solar plants must cover a huge area. Areas which are widely spacious and widely open such as deserts are the best place to build solar systems. Another disadvantage of the use of solar energy as alternative fuel is the huge capital investment entailed during initial building. It was estimated that as much as 3 percent of the world’s fossil fuel could be utilized in the production deployment of solar cells. Moreover, even though solar energy is considered as a clean energy, it does not mean that solar energy does not produce pollution. Some toxic materials are actually utilized during production of solar cells such as hydrofluoric acid, boron trifluoride and compounds of arsenic, cadmium, tellurium, selenium. These poisonous substances are used in large quantities hence the health of the people in charged of building and producing solar cells may be at risk (McKinney et al, 2007).
Photovoltaics and Concentrating Solar Power
In 1905, Albert Einstein provided a scientific explanation on the direct conversion of light into electricity. Modern photovoltaics in in fact based on Einstein’s essay on the law of photoelectric effect. Later on, a solar collector composed of copper coils and insulated box was produced by William J. Bailey of the Carnegie Steel Company. The design made by Bailey is actually the basis of the solar panels that are used currently. The publications of Einstein led to further investigations on the solar technology. In fact, due to the energy crisis, the passive solar buildings was used during World War II to supplement the huge demand of energy which was not sufficed by other energy sources. It took 50 years before the photovoltaic technology was utilized courtesy of the Bell Labs. The year 1954 marked the birth of photovoltaic technology in the United States. This occurred following the development of silicon photovoltaic cell by Daryl Chapin, Calvin Fuller, and Gerald Pearson at the Bell Labs. Bell Labs is the first solar cell which has the ability to convert light energy from the sun into power that can then be used to run electrical equipments. This means that the power generated from the conversion of solar energy can be used as electricity that will be used to run electrical equipments (Katsioloudis et al., 2009).
The Bell Telephone Laboratories also produced silicon solar cell which started with a 4 percent efficiently but increased to 11 percent efficiency (Katsioloudis et al., 2009). The photovoltaic energy is used to generate electricity directly from the sun. In fact at present, photovoltaic technology is one of the two means of harnessing solar energy to generate electricity. The photovoltaic technology is still evolving; from the silicon based solar cell used in 1950s, polycrystalline materials which are more efficient are now being used. Moreover, the use of photovoltaics remains confined in small scale applications as well as in residential use. It can be observed as being use ubiquitously used in various devices including calculators, highway signs and patios (Null, 2009). This technology is indeed beneficial however it is also hampered with several disadvantages. One of these disadvantages is the fact that this technology is very costly (Katsioloudis et al., 2009). In fact, the cost of generating electricity through photovoltaic technology can be several times the cost of fossil fuels. But with the progressive use of this technology it has been observed that the cost was constantly decreasing since 1970s. In 1975, it costs $70 to produce one watt of electricity whereas it only costs $2 per watt in 2006. The decreased price of production is translated to the increased sales and use of the photovoltaic systems (McKinney et al, 2007). Moreover, photovoltaics warrants the use of batteries to store the electricity generated.
Concentrating Solar Power (CSP) is one of two means of harnessing energy form the sun. At present CSP technology provides electricity to about half a million Californians which receive their power form the Mojave Desert. Wit this success, building more CSP plants in various regions around the world has been considered (Wolff, 2007). The CSP technology is based mainly on the solar motor developed by Mouchout (Null, 2009). Compared to photovoltaic, CSP do not utilize solar cells and does not need constant illumination, rather in CSP uses wide array of mirrors concentrated in a small area which would capture the energy from the sun. The energy trapped in these mirrors would be used to heat water to produce steam. Steam is the used to power turbines and generators. CSP is very effective if it was put up in wide open areas such as deserts. One of the advantages of CSP is that it does not require constant illumination because it has the ability to store the heat from the sun in salts such as nitrates, sodium or potassium. Unlike photovoltaics, CSP can run even at night or when there is storm. In conditions when the sun is not shining, the CSP would just utilize the heat in the salts to continuously provide power. The elimination of the necessity for batteries to store power makes CSP comparably cheaper than photovoltaics (Wolff, 2007).
The sun has an enormous amount of energy which is evident by the heat reaching the earth. This enormous amount of energy can be harnessed to fuel the industries around the world with a comparably clean form of energy. Indeed, environmental degradation attributed to the use of fossil fuels is so apparent thus increasing the concerns on the use of alternative use of energy. Moreover, there huge energy crisis is looming since the fossil fuel reserves are slowly exhausting. With these problems in front of humanity, there should be considerable effort to look for other alternative sources of energy. Solar energy has been sued since 1950s in the form of solar cells. Although this has not been used as extensively as other forms of energy, solar energy is very promising. Cost which is one of the hindrances of fully tapping solar energy, may not remain a problem anymore since there have been significant decrease in the cost of production of solar power plants. If fully supported, continued use of solar energy may eventually halt the current problems regarding energy and environmental degradation.
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McKinney, Michael L., Schoch, Robert M. and Yonavjak, Logan (2007). Environmental science: systems and solutions. Jones & Bartlett Publishers.
Null, Jan (2009). Harnessing the Sun: The Promises of Solar Energy. Weatherwise, 30-36.
Katsioloudis, Petros J., Bondi, Stella, Deal and Walter F. (2009). Energy from the Skies: Empowering Future Generations. Technology Teacher, 68 (6).
Sen, Zekāi (2008). Solar Energy Fundamentals and Modeling Techniques: Atmosphere, Environment, Climate Change and Renewable Energy. Springer.
Wolff, Gerry (2007). Bring Me Sunshine. Power Engineer, 22-25.